It is known to use a helical spring to connect a toggle member to a screw by turning the end of the screw to reduced size to mount a spring whose outer diameter matches the crest of the screw thread so that the turns of the outer diameter of the helical spring are extensions of the screw thread. Also, Leitner U.S. Pat. No. 3,175,452 attaches a flexible part of reduced diameter to which a toggle nut is connected, to the end of a screw which is to be inserted in a blind hole and later hopefully turns the toggle onto the reduced part and juggles it onto the screw. German Pat. No. 1,045,984 is similar. In practice it is exceedingly difficult to thread the screw into the nut after the nut has been inserted into a blind hole. A reduced diameter flexible portion gives no purchase on the threads of the nut to draw it toward the screw. The screw should be pushed toward the nut while turning but cannot be. Italian Pat. No. 483,279 shows a reduced diameter hook shaped member on the end of the screw and a separate pull cord which is supposed to provide the purchase to permit screwing the screw into the toggle member. Again, that would be exceedingly difficult to accomplish in fact since the parts are not aligned. U.S. Pat. No. 3,782,238 appears to involve a portion of a bolt turned to reduced diameter and bent to receive a toggle member similar to the Italian patent. The toggle cannot be engaged on the main bolt thread until after insertion in the hole. Threading then is difficult because the toggle is inaccessible.
In no case is an unmodified screw known to be used with a standard helical spring to engage a non-complementary hole in a unitary toggle member that is over-sized to the threads of the screw but large enough to receive the spring as an intermediate member overlapping between the screw threads and the threads of the toggle hole.